Back in mid-September, we reported on possible upcoming updates to the MacBook Pro lineup in the form of newer internal hardware, particularly faster Sandy Bridge CPUs. Now, new signs are supporting the rumor.

According to 9to5mac, two 13-inch models, two 15-inch models and one 17-inch model will be made available for a total of 5 new models. In fact, a number of new model names have reportedly been found in Apple’s inventory, the K90IA, K91A and K92A. The arrival of these new units is currently being blamed for the low online stock of existing MacBook Pro models.

Beyond the suspected CPU upgrades, the new “A” models are said to carry Bluetooth 4.0 as well. External updates to the chassis are unlikely and may not come until the next major update in 2012. By then, the MacBook Pros are expected to sport Intel’s 32nm Ivy Bridge chipsets for additional power savings and lower operating temperatures.

Apple, however, has yet to officially announce any additional MacBook Pro models, but with unknown model names supposedly found in their system, the updated units are practically confirmed to arrive. Exactly when that will be is still unknown.